1. In 2016, there were at least 566 freestanding EDs in the U.S. That's up 42 percent from 2015 and up 155 percent from 2008. Texas is home to 266 freestanding EDs, 204 of which are independent and 62 of which are hospital-owned. Texas, the focus state of UnitedHealth's report, began licensing freestanding EDs in 2010.

2. More than a quarter of all ED visits in Texas take place at a freestanding facility, according to the brief. In addition, freestanding EDs often treat nonemergent conditions: Just 2.3 percent of freestanding ED visits in the U.S. are emergent or require services unique to an ED, according to the brief.

3. The average cost of treating a common condition like fever and sore throat — which make up a large portion of visits at freestanding EDs — is $3,217 in Texas. That's 22 times higher than the $146 a physician office would charge, and 19 times higher than the $167 an urgent care center would charge.

4. Patients' out-of-pocket responsibility averages more than $800 at freestanding EDs in Texas, which are often placed in more affluent neighborhoods, according to the brief. Out-of-pocket expenses average less than $100 for patients who go to a physician office or urgent care center for common conditions.

5. "Shifting the site of care for common conditions in Texas from [freestanding] EDs to physician offices and urgent care centers would reduce costs by 95 percent, resulting in a savings of over $3,000 per visit," UnitedHealth said.